Reciprocating-piston compressor and control method therefor

ABSTRACT

The present disclosure relates to a reciprocating-piston compressor ( 10 ), including a control device ( 12 ), which control device is designed to control a flow rate of the reciprocating-piston compressor ( 10 ), in particular in a continuously variable manner, and which control device has an input ( 18 ) for feeding input information, in particular suction pressure or high pressure of a corresponding compressor ( 10 ), and has at least one output ( 20 ) for controlling a control element ( 16 ), wherein the control device ( 12 ) is designed to generate a digital output signal, wherein the control element has a digitally controllable control valve ( 16 ), wherein the reciprocating-piston compressor ( 10 ) has at least one suction-gas volume ( 22 ) and at least one high-pressure volume ( 24 ), wherein a connection ( 26 ) is formed between the at least one suction-gas volume ( 22 ) and the at least one high-pressure volume ( 24 ) of the reciprocating-piston compressor ( 10 ), wherein the digitally controllable control valve ( 16 ) is arranged in the connection ( 26 ), wherein the reciprocating-piston compressor ( 10 ) has a shut-off device, in particular a valve, further in particular a check valve ( 28 ), which is arranged downstream of the high-pressure volume ( 24 ), as regarded in a flow direction of the refrigerant during normal operation of the reciprocating-piston compressor ( 10 ), wherein the at least one suction-gas volume and the at least one high-pressure volume and the control valve ( 16 ) are integrated into the reciprocating-piston compressor ( 10 ). The disclosure further relates to a refrigerating or air-conditioning installation or heat pump having a corresponding compressor ( 10 ), and to a corresponding control method.

The present invention relates to a reciprocating-piston compressor as per the preamble of patent claim 1, and to a refrigeration or air-conditioning installation which has the reciprocating-piston compressor, or a heat pump which has the reciprocating-piston compressor, as per claims 6 and 7. The concept of the present invention also includes a corresponding regulating method.

Refrigeration installations are often operated with reciprocating-piston compressors. Examples of these may be found inter alia in the field of bus air-conditioning systems, where, in a corresponding refrigeration installation (air-conditioning installation), there is arranged a reciprocating-piston compressor which is driven by the crankshaft of the drive engine via a belt drive and a magnetic coupling. The compressor can be activated and deactivated by way of the magnetic coupling. The activation and deactivation however acts on the compressor as a whole, and thus on the overall power imparted by the compressor (100% on-off). Other examples can be found in the field of mobile and static air-conditioning systems, mobile and static refrigeration systems, that is to say for example in the field of transport refrigeration systems and supermarket refrigeration systems, and in the field of heat pumps.

The activation and deactivation necessitates a transient operation of the compressor and also leads to high peak loads during the operation thereof. The switching frequency is in this case basically limited by the masses to be moved and by the switching work of the coupling.

In the case of the compressors, it is the case, for example in the field of bus air-conditioning systems, that use is predominantly made of four-cylinder reciprocating-piston compressors, in which two individual cylinder banks are arranged in a V configuration. In other applications, use is made of other reciprocating-piston compressors with any desired number of cylinders, wherein the cylinders may or may not be arranged in cylinder banks or divided into cylinder banks.

When operated on a diesel engine, compressors for example in mobile applications, in particular in mobile air-conditioning applications, are constantly operated at a rotational speed which corresponds to the driving operation, which rotational speed does not correspond to a rotational speed at which the compressor would impart the desired cooling power. For this reason, there is a need for constant correction of the cooling or refrigeration power.

A similar problem also arises for example in some transport refrigeration installations.

It is known that this can, for example in passenger motor vehicles, be partially compensated by way of stroke-regulated axial piston compressors. There, the stroke is regulated in continuously variable fashion to near to zero, and the undesired rotational speed influence is partially compensated in this way. This type of construction, which is conventional in the case of small compressors, dispenses with a dedicated oil system, and functions adequately well in limited installations with limited service lives for passenger motor vehicles. Until now, however, there has been no success in transferring this to series production in utility vehicles with their higher power levels and longer demanded service lives.

In the field of bus air-conditioning systems, it is known, in the case of four-cylinder V-configuration compressors, for one cylinder bank (=two cylinders=50%) to be deactivated or placed into a state in which no delivery rate (delivery power) is imparted by the corresponding cylinder bank. This is realized by virtue of the suction gas flow for the corresponding cylinder bank being shut off. The compressor then runs virtually with a zero-delivery action, effects compression against final pressure and re-expands the gas, wherein the compression work is transmitted back to the crankshaft. With such regulation, it is already possible for a bus air-conditioning system to be regulated somewhat more finely, specifically in 50% steps, though this is not always adequate if it is sought to achieve high regulation quality.

Accordingly, it is an object of the present invention to specify a reciprocating-piston compressor for a wide variety of fields of use, for example refrigeration, air-conditioning or heat pump applications, which reciprocating-piston compressor exhibits increased regulation quality in relation to the prior art. It is also an object of the present invention to specify corresponding installations, and a corresponding regulating method.

Said object is achieved according to the invention by way of a reciprocating-piston compressor as per patent claim 1. The second aspect of the object is achieved by way of installations as per claims 6 and 7. The method-related aspect of the object is achieved by way of a method as claimed in claim 8.

A corresponding reciprocating-piston compressor has a regulating device which is provided for the in particular continuously variable regulation of a delivery rate of the reciprocating-piston compressor, which regulating device has an input for the supply of input information, in particular suction pressure or high pressure of the compressor, and has at least one output for the actuation of a regulating element. The regulating device is designed to generate a digital output signal, wherein the regulating element has a digitally actuable regulating valve. The reciprocating piston compressor has at least one suction-gas volume and at least one high-pressure volume, wherein a connection is formed between the at least one suction-gas volume and the at least one high-pressure volume of the refrigeration installation, and wherein the digitally actuable regulating valve is arranged in the connection. Furthermore, the reciprocating-piston compressor has a shut-off device, in particular a valve, furthermore in particular a check valve, which is arranged downstream of the one/a respectively assigned high-pressure volume as viewed in a flow direction of the refrigerant during normal operation of the compressor. The at least one suction-gas volume and the at least one high-pressure volume and the regulating valve are integrated into the reciprocating-piston compressor.

The connection between high-pressure volume and suction volume of the compressor can, with simultaneous closure of a shut-off device which is assigned to the high-pressure side and which is arranged downstream of the high-pressure volume as viewed in the operational flow direction of the refrigerant, be opened, whereby pistons or cylinder banks assigned to the two abovementioned volumes, or if appropriate all of the cylinders or cylinder banks of the compressor, can be placed into a state with a zero-delivery action with regard to refrigerant. As a result of the integration of the high-pressure volume into the compressor, as small a high-pressure volume as possible is ensured, which yields expedient operation of the compressor in terms of energy.

With regard to the installation aspect, the object is achieved by way of devices as per claim 6 or 7, which have a corresponding reciprocating-piston compressor.

It is proposed that the entire compressor and/or cylinder banks or cylinder groups, possibly also individual cylinders, be equipped with fast-switching regulation capability (digital regulation). In this way, the compressor can, in effect, be regulated in continuously variable fashion from 100% to preferably approximately 10% of its nominal delivery volume or of its maximum delivery volume.

The scope of the present invention also encompasses a method for regulating a delivery rate of a reciprocating-piston compressor or of a refrigeration installation equipped therewith, by way of a digital signal.

It is finally pointed out that the concept of the present invention also encompasses the use of a digitally actuable valve as a regulating valve for the delivery rate of a reciprocating-piston compressor in a regulating device for an air-conditioning installation.

Further optional features of the invention are specified in the subclaims and in the following description of the figures. In the description of the figures, the present invention will be described on the basis of the example of a device for bus air-conditioning (refrigeration installation for bus air-conditioning or bus air-conditioning system). It is however pointed out at this juncture that a refrigeration installation according to the invention may also be used in many applications, for example in a refrigeration installation for a trailer, generally in a transport refrigeration installation, or else in a static refrigeration installation (for example supermarket refrigeration system).

The described respective features may be realized individually or in any desired combinations. The invention will accordingly be described below with reference to the appended drawings based on exemplary embodiments. In the drawings:

FIG. 1 is a schematic illustration of a bus, with a schematic illustration of a first possible embodiment of the invention used in an air-conditioning system of said bus;

FIG. 2 shows a partial view of the compressor as schematically illustrated in FIG. 1,

FIGS. 3 and 4 each show a schematic view of a detail (sectional view) of the compressor as per FIG. 2; and

FIG. 5 is a schematic illustration of a compressor which is used in a second possible embodiment of a refrigeration installation according to the invention.

As illustrated in FIG. 1, a refrigeration installation or air-conditioning installation 1 in the form of a bus air-conditioning system 1 has, as major constituent parts, a compressor 10 for the compression of refrigerant, which compressor is in the form of a reciprocating-piston compressor, and a regulating device 12, which has a regulator 14 and a regulating element in the form of a shut-off device or a valve 16. A compressor according to the invention may be used not only in the air-conditioning field but also, for example, in the fields of static and mobile refrigeration and the field of heat pumps.

The regulating device 12 furthermore has an input 18 for the supply of input information, which in the embodiment described here is represented by a suction pressure of the compressor 10, and an output 20 for the actuation of the regulating element (valve 16), and a delivery volume determination device for determining a desired delivery volume in a manner dependent on an input signal supplied to the input 18 and for generating a corresponding output signal to be supplied to the output 20. While it is the case in refrigeration installations or air-conditioning installations that the input variable is preferably the suction pressure of the compressor 10, it is the case in heat pumps that the input variable is for example preferably the high pressure, that is to say the pressure that prevails at the high-pressure side of the compressor 10.

The regulating device 12 is designed to generate a digital output signal. For implementing the digital output signal, the valve 16 that regulates the delivery volume of the compressor 10 is designed as a digitally actuable electromagnetic valve. Other valve types are alternatively also conceivable, in particular electromechanical or else mechanically, pneumatically or hydraulically actuable valves or other shut-off devices (slide valves and the like).

The refrigeration installation 1 has a suction-gas volume 22 and a high-pressure volume 24, wherein the suction-gas volume 22 is arranged upstream of the cylinders of the compressor 10 and the high-pressure volume 24 is arranged downstream of the cylinders of the compressor 10, wherein the directional terms “upstream” and “downstream” are defined by the flow direction of the refrigerant during normal operation of the refrigeration installation 1. Between the suction-gas volume 22 and the high-pressure volume 24, a connection 26 is formed in the manner of a bore or cutout for example in the housing of the compressor 10 or else as a pipeline, wherein the digitally actuable valve 16 is arranged in the connection 26 and can open and shut off or close said connection.

The refrigeration installation 1 furthermore has a second shut-off device in the form of a check valve 28 (second valve) which is arranged downstream of the high-pressure volume 24. Instead of a check valve 26, any other shut-off device (slide valve, valve, for example electromechanically actuated or electromagnetically actuated or else pneumatically actuated valve, or an aperture or the like) is also conceivable.

The suction-gas volume 22 and the high-pressure volume 24 are connected to one another by the abovementioned connection 26, for example pipeline (bypass line) which can be opened and closed by the digitally actuable valve 16 such that the suction-gas volume 22 and the high-pressure volume 24 are directly (fluidically) connected to one another when the valve 16 is in an open position.

When the valve 16 is in a closed position, no direct connection exists between the suction-gas volume 22 and the high-pressure volume 24. The compressor 10 is in normal operation (in this regard, cf. also FIG. 3) in which refrigerant is conducted from the suction-gas volume 22 into the cylinders, is compressed there, and is then discharged into the high-pressure volume 24 and made available to the bus air-conditioning system 1 (the path of the refrigerant is indicated in each case by arrows).

However, when the valve 16 is in its open position (in this regard, cf. also FIG. 4), there is a “short circuit” between the suction-gas volume 22 and high-pressure volume 24. When the valve 16 is in an open position, the check valve 28 closes owing to the high pressure, and thus keeps the high pressure away from the working chambers of the compressor. Thus, the power consumed by the compressor falls to the unavoidable value that arises from the internal losses of the compressor, for example at the working valves. In alternative embodiments, some other shut-off device is closed, for example by way of the regulating device 12. Thus, the compressor 10 is “deactivated” because the refrigerant delivered by the cylinders flows from the high-pressure volume 24 back into the suction-gas volume 22 and, from there, passes into the cylinders and then in turn into the high-pressure volume 24.

The opening duration of the valve 16 can, by way of the regulating device 12, be realized with any desired, continuously variable timing (pulsing), such that a delivery rate of the compressor 10 can be adjusted from, in principle, 0% to 100% in continuously variable or almost continuously variable fashion. In the embodiment described here, the regulating device 12 is however designed such that a minimum delivery volume of 5% to 10% is ensured in order to cool the compressor 10. In the case of exclusively air-cooled compressors, this can be dispensed with.

It is additionally pointed out that the described refrigeration installation 1 has a condenser 30, an expansion element in the form of an expansion valve 32, and an evaporator 34 for the air-conditioning of the vehicle (bus) 36/for the cooling of the volume to be cooled. A setpoint value with the aid of which the suction pressure that is desired and thus to be set is determined is input from the volume (in the described embodiment from the vehicle 36) in which air-conditioning is to be performed.

As can be seen from FIGS. 2 to 4, the described embodiment of a refrigeration installation 1 according to the invention has the suction-gas volume 22 and the high-pressure volume 24 integrated in the compressor 10. The connection 26 between the suction-gas side and the high-pressure side is, between the suction-gas volume 22 and the high-pressure volume 24, in this case formed preferably in the form of a duct (alternatively as a bore or as a cutout formed during the course of the casting of the corresponding components, alternatively also as a pipeline). As in the embodiment discussed above, the valve 16 is arranged in the connection 26 (duct) and is thus likewise integrated into the compressor 10. Again, all conceivable types of valves and other shut-off devices are conceivable, as have already been presented in conjunction with the embodiment discussed above. An integration of the volumes and of the valve into the compressor 10 may be advantageous in particular in installations in which high pressures are attained. The mode of operation in the second embodiment is identical to that of the first embodiment.

As can be seen from the schematic illustration in FIG. 5, a compressor 10 of a second embodiment of a refrigeration installation according to the invention, which compressor is likewise in the form of a reciprocating-piston cylinder, has two cylinder groups in the form of two cylinder banks 40 (the cylinders need not necessarily be grouped as cylinder banks 40; other criteria for grouping are conceivable).

The refrigeration installation 1, more specifically the reciprocating-piston compressor 10 of the refrigeration installation 1, has, per cylinder bank 40 (in alternative embodiments, per cylinder group or per cylinder), one suction-gas volume 22 for feeding refrigerant to the respective cylinder bank 40 and one high-pressure volume 24 for the discharge of the refrigerant. The corresponding suction-gas volumes 22 are arranged upstream of the respectively associated cylinder bank 40, whereas the corresponding high-pressure volumes 24 are arranged downstream of the respectively associated cylinder bank 40. In the illustrated embodiment, the suction-gas volumes 22 and the high-pressure volumes 24 are arranged within, that is to say integrated into, the compressor 10. Between the suction-gas volume 22 assigned to the first cylinder bank 40 and the high-pressure volume 24 assigned to the first cylinder bank 40, there is formed a connection 26 which connects the two volumes to one another. A digitally actuable valve 16 is arranged in the connection. An analogous construction is realized for the volumes assigned to the second cylinder bank 40. Between the suction-gas volume 22 assigned to the second cylinder bank 40 and the high-pressure volume 24 assigned to the second cylinder bank 40, there is formed a further (second) connection 26 which connects the two volumes to one another. A digitally actuable valve (third valve) 16 is arranged in the connection. The connections 26 are in the form of pipelines.

The valves 16 are designed analogously to the valve 16 already described in the first and second embodiments, and may also be substituted by any other desired shut-off device, wherein at least one of the shut-off devices must be digitally actuable in order to realize the desired regulating precision. It would alternatively also be conceivable that only for volumes assigned to one cylinder bank 40 a connection 26 (for example pipeline or duct) is provided. The valves 16 are controlled by the regulating device 12. In this embodiment, too, both the connection(s) 26 and the high-pressure volumes and suction-gas volumes are arranged so as to be integrated in the compressor 10.

By way of a construction according to the second embodiment, a deactivation and activation of individual cylinder groups (cylinder banks 40) is possible. It is accordingly proposed for cylinder banks 40 or cylinder groups, or if appropriate also individual cylinders, to be actuated with fast-switching regulation capability. In this way, the compressor 10 can be regulated in continuously variable fashion or virtually continuously variable fashion, or in any desired steps, from 100% down to approximately 10%, wherein the lower limit is determined by thermal aspects and by the oil management of the compressor 10. Here, the switching of the cylinder banks 40 or cylinder groups, or if appropriate also of individual cylinders, may in this case be performed asynchronously, such that the total time with zero-delivery action can be limited.

It is pointed out at this juncture that the concept of the present application also encompasses an arrangement of the connection(s) 26 and/or the valve(s) 16 and/or the suction-gas volume(s) and/or the high-pressure volume(s) outside the compressor. This constitutes a simple construction which is however somewhat less effective from an energy aspect than the embodiments described above, in particular because the high-pressure volume or the high-pressure volumes are larger than in the embodiments described above. Furthermore, in the case of the components being integrated into the compressor, uncomplicated installation and also uncomplicated construction by the manufacturer of the respective air-conditioning installation or refrigeration installation or heat pump etc. are possible.

The following is given as an example for possible regulation: in the case of desired refrigerant delivery corresponding to 50-100% of the nominal rate, a cylinder bank 40 operates with timing (pulsing) down to complete deactivation (at 50%); in the case of desired refrigerant delivery corresponding to 50-10% of the nominal rate, both banks operate with timing (pulsing) with increasing overlap. For example, at 10%, each bank runs 6 s per minute in alternating fashion.

A further advantage of said regulation is that the start-up torque of the compressor 10 can be limited, for example by virtue of all of the cylinders being deactivated upon starting. In this way, it is possible to limit the size of couplings and drives via which corresponding compressors 10 are generally driven. It is also possible for the torque to be generally controlled and limited in order to also protect the coupling against possible overloading during operation.

A further possibility is for one or more cylinder banks 40 or cylinder groups or cylinders to be deactivated upon every activation process of the coupling. In this way, the switching work of the coupling is reduced. This possibility also exists upon the deactivation of the compressor 10, such that the torque is reduced also during the separation of the compressor 10 from the drive.

In the case of peripheral systems and individual compressor systems such as in buses or in transport refrigeration systems, an unloaded start-up of the compressor 10 is of particular significance because the drive components can be dimensioned to be of correspondingly lower strength. In this respect, reference is also made here in particular to an application as a rate (power) regulator for CO₂ compressors, which, with other methods, can generate excessive amounts of heat and, at the same time, can get to a dry ice-region (dry-ice regime).

It is pointed out at this juncture that the concept of the present application also encompasses a corresponding method for regulating an air-conditioning system 1. The method according to the invention for regulating the air-conditioning system 1 is presented as follows.

The method according to the invention serves for the regulation of a reciprocating-piston compressor 10, for example of a refrigeration or air-conditioning installation 1 or of a heat pump, wherein the regulation of the air-conditioning installation 1 is effected by regulation of the delivery rate of the compressor 10. The regulation of the delivery rate is realized by way of at least one digital signal. The digital signal or digital signals may be supplied to one or more digitally actuable regulating valve(s) 16. In possible embodiments, the refrigeration installation 1 has at least one suction-gas volume 22 and at least one high-pressure volume 24, wherein a connection 26 is formed between the at least one suction-gas volume 22 and the at least one high-pressure volume 24 of the reciprocating-piston compressor 10, wherein the regulation of the delivery rate of the compressor 10 is performed by opening and closing of the connection 26 in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve 16.

The refrigeration installation may have multiple cylinder groups, in particular cylinder banks 40, and more than one suction-gas volume 22, in particular one suction-gas volume 22 for each cylinder group, and more than one high-pressure volume 24, in particular one high-pressure volume 24 for each cylinder group, wherein at least one connection 26 is formed between one of the suction-gas volumes 22 and a corresponding high-pressure volume 24 of the refrigeration installation 1. The regulation of the delivery rate of the compressor 10 is performed by opening and closing of the connection 26 in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve 16.

A connection 26 is preferably formed between each of the suction-gas volumes 22 and each corresponding high-pressure volume 24 of the refrigeration installation 1, wherein the regulation of the delivery rate of the compressor 10 is performed by opening and closing of the connections 26 in a manner controlled by the digital signal, in particular by way of digitally actuable regulating valves 16. The opening and closing of connections 26 assigned to different cylinder groups is preferably performed asynchronously during the operation of the refrigeration installation 1.

One possible embodiment of a method according to the invention is a method for regulating a reciprocating-piston compressor 10 which, as already discussed, has a regulating device 12 and is provided for compressing refrigerant. The regulation of the reciprocating-piston compressor 10 is effected by regulation of the delivery rate of the compressor 10, wherein the regulation of the delivery rate is realized by way of at least one digital signal, wherein the digital signal or digital signals are supplied to one or more digitally actuable regulating valve(s) 16. The reciprocating-piston compressor 10 has at least one suction-gas volume 22 and at least one high-pressure volume 24, wherein a connection is formed between the at least one suction-gas volume 22 and the at least one high-pressure volume 24 of the refrigeration installation, wherein the regulation of the delivery rate of the compressor is performed by opening and closing of the connection in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve 16. The reciprocating-piston compressor 10 has a shut-off device 28 which is arranged downstream of the high-pressure volume 24 as viewed in a flow direction of the refrigerant during normal operation of the reciprocating-piston compressor 10, wherein the shut-off device 28 is closed when the connection 26 is open, and wherein the shut-off device 28 is open when the connection 26 is closed.

The regulating device actuates one or more regulating valves such that a delivery volume of 5% to 10% of the nominal delivery volume or maximum delivery volume of the compressor 10 is provided as a minimum delivery volume, and/or such that 100% of the nominal delivery rate or nominal delivery volume or of the maximum delivery volume or of the maximum delivery rate is provided as a maximum delivery volume. It is preferably the case that continuous variation, or continuously variable regulation, is performed between the minimum delivery volume and the maximum delivery volume.

Furthermore, the following method is encompassed by the present disclosure:

1. A method for regulating a reciprocating-piston compressor having a regulating device, wherein the regulation of the refrigeration installation is effected by regulation of the delivery rate of the compressor, wherein the regulation of the delivery rate is realized by way of at least one digital signal.

2. The method according to 1., wherein the digital signal or digital signals are/is supplied to one or more digitally actuable regulating valves.

3. The method according to 1. or 2.,wherein the refrigeration installation has at least one suction-gas volume and at least one high-pressure volume, wherein a connection is formed between the at least one suction-gas volume and the at least one high-pressure volume of the refrigeration installation, wherein the regulation of the delivery rate of the compressor is performed by opening and closing of the connection in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve.

4. The method according to 1., 2. or 3., wherein the refrigeration installation has multiple cylinder groups, in particular cylinder banks, and more than one suction-gas volume, in particular one suction-gas volume for each cylinder group, and more than one high-pressure volume, in particular one high-pressure volume for each cylinder group, wherein at least one connection is formed between one of the suction-gas volumes and a corresponding high-pressure volume of the refrigeration installation, wherein the regulation of the delivery rate of the compressor is performed by opening and closing of the connection in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve.

5. The method according to 4., wherein a connection is formed between each of the suction-gas volumes and a corresponding high-pressure volume of the refrigeration installation, wherein the regulation of the delivery rate of the compressor is performed by opening and closing of the connections in a manner controlled by the digital signal, in particular by way of digitally actuable regulating valves.

6. The method according to one of points 1. to 5., wherein the compressor has one or more feed line(s) for refrigerant to be compressed, wherein, in the case of a compressor which has multiple cylinder groups, in particular cylinder banks, it is in particular the case that one feed line is provided for each cylinder group, wherein the regulation of the delivery rate is performed by opening and closing of the connection in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve.

7. The method according to one of points 1. to 6., wherein the regulating device actuates one or more regulating valves such that a delivery volume of 5% to 10% of the nominal delivery volume or maximum delivery volume of the compressor is provided as a minimum delivery volume.

The disclosure of the present application also encompasses the following:

1. A regulating device (12) for an air-conditioning installation (1), which regulating device is provided for the regulation of a delivery rate of a reciprocating-piston compressor (10), which regulating device has an input (18) for the supply of input information, in particular suction pressure of a corresponding compressor (10), and has at least one output (20) for the actuation of a regulating element (16), characterized in that

-   -   the regulating device (12) is designed to generate a digital         output signal.

2. The regulating device (12, 112) according to 1, characterized in that

-   -   the regulating element has a digitally actuable regulating valve         (16).

3. A refrigeration installation (1) having a regulating device (12) and having a reciprocating-piston compressor (10) for the compression of refrigerant, characterized in that

-   -   the regulating device is a regulating device (12) according         to 1. or 2.

4. The refrigeration installation (1) according to 3, characterized in that

-   -   the compressor (10, 110) has multiple cylinder groups, in         particular cylinder banks (40, 124).

5. The refrigeration installation (1) according to 3 or 4, characterized in that

-   -   the refrigeration installation (1) has at least one suction-gas         volume (22) and at least one high-pressure volume (24), wherein         a connection (26) is formed between the at least one suction-gas         volume (22) and the at least one high-pressure volume (24) of         the refrigeration installation (1), wherein the digitally         actuable regulating valve (16) is arranged in the connection         (26).

6. The refrigeration installation (1) according to 4 or 5, characterized in that

-   -   the refrigeration installation (1) has more than one suction-gas         volume (22), in particular one suction-gas volume (22) for each         cylinder group, and more than one high-pressure volume (24), in         particular one high-pressure volume (24) for each cylinder         group, wherein at least one connection (26) is formed between         one of the suction-gas volumes (22) and a corresponding         high-pressure volume (24) of the refrigeration installation (1),         wherein the/a digitally actuable regulating valve (16) is         arranged in the connection (26).

7. The refrigeration installation (1) according to 6, characterized in that

-   -   a connection (26) is formed between each suction-gas volume (22)         and between each high-pressure volume (24) respectively         corresponding therewith, wherein a digitally actuable regulating         valve (16) is arranged in the respective connection (26).

8. The refrigeration installation (1) according to one of 5 to 7, characterized in that

-   -   the at least one suction-gas volume (22) or multiple suction-gas         volumes (22) of the refrigeration installation (1) is/are formed         at least partially by a compressor suction-gas volume (22)         integrated in the compressor (10) or multiple compressor         suction-gas volumes (22) in each case integrated in the         compressor (10), in particular suction chamber(s), and the at         least one high-pressure volume (24) or multiple high-pressure         volumes (24) is/are formed at least partially by a compressor         high-pressure volume (24) integrated in the compressor (10) or         multiple compressor high-pressure volumes (24) in each case         integrated in the compressor (10), in particular pressure         chamber(s), wherein in each case one connection (26) is arranged         between one or more compressor suction-gas volumes (22)         integrated in the compressor (10) and one or more compressor         high-pressure volumes (24) integrated in the compressor (10).

9. The refrigeration installation (1) according to one of 3 to 8, characterized in that

-   -   the refrigeration installation (1) has a shut-off device, in         particular a valve, furthermore in particular a check valve (28)         which is arranged downstream of the high-pressure volume (24) as         viewed in a flow direction of the refrigerant during normal         operation of the refrigeration installation (1).

10. The refrigeration installation (1, 101) according to one of 3 to 8, characterized in that

-   -   the compressor (10) has one or more feed lines for the         refrigerant to be compressed, wherein, in the case of a         compressor (10) which has multiple cylinder groups, in         particular cylinder banks (40), it is the case in particular         that one feed line is provided for each cylinder group, wherein         the digitally actuable regulating valve (16) is arranged in one         of the feed lines.

11. The refrigeration installation (1) according to 10, characterized in that

-   -   a digitally actuable regulating valve (16) is arranged in each         of the feed lines.

12. The refrigeration installation (1) according to one of 3 to 11, characterized in that

-   -   the refrigeration installation (1), in particular the regulating         device (12), is designed to regulate the delivery volume of the         compressor (10) from 5%, in particular 10%, of a nominal         delivery rate or of a maximum delivery rate up to 100% thereof,         in particular in continuously variable fashion.

Even though the invention has been described on the basis of embodiments with set combinations of features, it however also encompasses the conceivable further advantageous combinations such as are specified in particular, but not exhaustively, by the subclaims. All of the features disclosed in the application documents are claimed as being essential to the invention where novel, individually or in combination, in relation to the prior art.

LIST OF REFERENCE SIGNS

1 Refrigeration installation or air-conditioning installation

10 Compressor

12 Regulating device

14 Regulator

16 Regulating element or valve

18 Input

20 Output

22 Suction-gas volume

24 High-pressure volume

26 Connection

28 Check valve

30 Condenser

32 Expansion valve

34 Evaporator

36 Vehicle (bus)

40 Cylinder bank 

1. A reciprocating-piston compressor having a regulating device which is provided for the in particular continuously variable regulation of a delivery rate of the reciprocating-piston compressor, which regulating device has an input for the supply of input information, in particular suction pressure or high pressure of a corresponding compressor, and has at least one output for the actuation of a regulating element, wherein the regulating device is designed to generate a digital output signal, wherein the regulating element has a digitally actuable regulating valve, wherein the reciprocating-piston compressor has at least one suction-gas volume and at least one high-pressure volume, wherein a connection is formed between the at least one suction-gas volume and the at least one high-pressure volume of the reciprocating-piston compressor, wherein the digitally actuable regulating valve is arranged in the connection, wherein the reciprocating-piston compressor has a shut-off device, in particular a valve, furthermore in particular a check valve, which is arranged downstream of the high-pressure volume as viewed in a flow direction of the refrigerant during normal operation of the reciprocating-piston compressor, wherein the at least one suction-gas volume and the at least one high-pressure volume and the regulating valve are integrated into the reciprocating piston compressor.
 2. The reciprocating-piston compressor as claimed in claim 1, wherein the compressor has multiple cylinder groups, in particular cylinder banks.
 3. The reciprocating-piston compressor as claimed in claim 1, wherein the reciprocating-piston compressor has more than one suction-gas volume, in particular one suction-gas volume for each cylinder group, and more than one high-pressure volume, in particular one high-pressure volume for each cylinder group, wherein at least one connection is formed between one of the suction-gas volumes and a corresponding high-pressure volume of the reciprocating-piston compressor, wherein the/a digitally actuable regulating valve is arranged in the connection.
 4. The reciprocating-piston compressor as claimed in claim 3, wherein a connection is formed between each suction-gas volume and between each high-pressure volume respectively corresponding therewith, wherein a digitally actuable regulating valve is arranged in the respective connection.
 5. The reciprocating-piston compressor as claimed in claim 1, wherein the reciprocating-piston compressor, in particular the regulating device, is designed to regulate the delivery volume of the compressor from 5%, in particular 10%, of a nominal delivery rate or of a maximum delivery rate up to 100% thereof, in particular in continuously variable fashion.
 6. A refrigeration installation or air-conditioning installation having a reciprocating-piston compressor as claimed in claim
 1. 7. A heat pump having a reciprocating-piston compressor as claimed in claim
 1. 8. A method for regulating a reciprocating-piston compressor which has a regulating device and which is provided for the compression of refrigerant, wherein the regulation of the reciprocating-piston compressor is effected by regulation of the delivery rate of the compressor, wherein the regulation of the delivery rate is realized by way of at least one digital signal, wherein the digital signal or digital signals are supplied to one or more digitally actuable regulating valve(s), wherein the reciprocating-piston compressor has at least one suction-gas volume and at least one high-pressure volume, wherein a connection is formed between the at least one suction-gas volume and the at least one high-pressure volume of the reciprocating-piston compressor, wherein the regulation of the delivery rate of the compressor is performed by opening and closing of the connection in a manner controlled by the digital signal, in particular by way of the digitally actuable regulating valve, wherein the reciprocating-piston compressor has a shut-off device which is arranged downstream of the high-pressure volume as viewed in a flow direction of the refrigerant during normal operation of the reciprocating-piston compressor, wherein the shut-off device is closed when the connection is open, and wherein the shut-off device is open when the connection is closed.
 9. The method as claimed in claim 8, wherein the regulating device actuates one or more regulating valves such that a delivery volume of 5% to 10% of the nominal delivery volume or maximum delivery volume of the compressor is provided as a minimum delivery volume, and/or such that 100% of the nominal delivery rate or nominal delivery volume or of the maximum delivery volume or of the maximum delivery rate is provided as a maximum delivery volume.
 10. The method as claimed in claim 8, wherein continuous variation, or continuously variable regulation, is performed between the minimum delivery volume and the maximum delivery volume. 